blog

We’ve not had any decent cell biology here for a while, but there’s a rather nice controversy that boiled up last year about the presence—or otherwise—of adherens junctions—focal contacts—in 3D cell cultures. A paper from Denis Wirtz’s lab made the rather striking claim that live cells migrating through a (more physiological) three-dimensional matrix do not form the focal adhesions that characterize cells in 2D culture. The usual suspects of focal adhesions—vinculin, paxillin, talin, alpha-actinin, zyxin, VASP, focal adhesion kinase—were present, but distributed diffusely throughout the cytoplasm.

The paper attracted no fewer than seven evaluations and a comment, giving it an F1000 Factor of 17. Clearly, were these results to be replicated it would be a very interesting and important finding indeed.

Talin and actin

But at the meeting of the American Society for Cell Biology in December, we heard rumours of a paper in press refuting this finding. And indeed, just before Christmas came the news (again in Nature Cell Biology) that reducing background fluorescence reveals adhesions in 3D matrices. Fraley et al. have responded, although Faculty Member Ken Yamada remains unconvinced by their arguments in his evaluation.

Ken, who I interviewed early last year for a The Scientist article on a novel and relatively easy way of looking at three dimensional growth in culture, admits there is a problem for us mortals:

Consequently, readers might seem to be left with a dilemma, because these two excellent research teams present contradictory findings using the same type of 3D collagen gel and the same cell lines.

He does, however, come out pretty strongly on the side of Kubow and Horwitz, saying

If one research group sees and quantifies a structure and another group reports that they cannot see it, the structure presumably exists unless it can be shown to be an experimental artifact – which does not appear to be the case here. It will be interesting to learn later what experimental problems encountered by Fraley et al. limited their visibility of 3D adhesions, which may help others perform these types of study in the future.

Reinhard Fässler and Herbert Schiller have also independently recommended the Kubow and Horwitz paper as an F1000 must read.

So what happens now? According to Ken Yamada, the field can now proceed to characterize these structures for their tissue-specificity and functions . And breathe a sigh of relief, presumably.